The present invention relates to an optical information reading device adapted to read, by means of a light beam, information reproduced from an information carrier such as a video disc, a P.C.M. audio disc or the like carrying the information in the form of convexities and concavities or variations in a light reflection factor.
In the reproduction of recorded signals from the carrier of the type mentioned above, it is possible to reduce the size of the reproducing apparatus as a whole by the use of a radiant ray source having a minute light emitting surface such as a semiconductor laser. For further reducing the size of the apparatus, it is necessary to overcome the problem of difficulty in making the path of the light beam short.